Extraperiosteal Plating of Pronation-Abduction Ankle Fractures

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T HE JOURNAL OF BONE & JOINT SURGERY · SURGICAL TECHNIQUES MARCH 2008 · VOLUME 90-A · SUPPLEMENT 2, PART 1 · JBJS.ORG
placed medial malleolar
fragment 2 . Thus, an anatomic reduction
of a supracollicular medial
malleolar fracture restores
medial support, gains talar congruence,
and assists with reduction
of the lateral malleolus 2,3
(Fig. 2-A). The incision used on
the medial side is slightly concave
anteriorly and is centered over
the medial malleolus, as this allows
both visualization of the reduction
and placement of the
screws (Fig. 2-B). Bicortical lagscrew
fixation, perpendicular to
the fracture line, is preferred to
increase the stability of the fixation
and to compress across the
fracture site (Fig. 3).
Attention is then turned to
the lateral side. The ankle should
be positioned with bolsters under
the ankle joint and not under
the heel. Bolsters under the heel
can cause anterior subluxation of
the talus and a malreduction.
The foot is adducted and medially
translated to center the talus
in the mortise, which aids in fibular
alignment. Because the lateral
ankle ligaments are intact in
this injury pattern, reducing the
talus under the plafond usually
aligns the distal fibular fragment
and restores fibular length. Fluoroscopic
imaging at this point allows
an assessment of fibular
length. The lateral cortex of the
fibula is comminuted, but the
medial cortex typically starts as a
transverse fracture line, so one
can evaluate the reduction at this
location to assess length (Fig. 4).
Finally the talocrural angle on
the affected side is compared
with the contralateral, normal
ankle to confirm fibular length 4 .
As the talocrural angle is not related
to the size of an image, fluoroscopic
evaluation is not
affected by magnification, as are
other measures of fibular length.
After determining the necessary
manipulation of the foot that
recreates fibular length, one can
proceed. (For additional techniques
to gain fibular length, see
separate section below.)
Once the general reduction
of the fibula can be obtained, the
incision is made. The incision is
centered over the posterior onehalf
of the fibula. When the incision
has been made through the
skin, care is taken not to incise
the periosteum. It is found immediately
subcutaneously and
often has small rents in it as part
of the injury, which can make it
difficult to recognize. Sharp
Weitlaner retractors can aid by
applying tension to the skin,
helping to peel the subcutaneous
tissues from the periosteum. The
periosteum is left entirely intact;
individual fracture fragments are
not identified, stripped, or further
handled. Once the dissection
is at the level of the
periosteum (Fig. 5), all retractors
are removed from the
wound as they can shorten the
fibula because of the tension
placed on the surrounding soft
tissues. Reduction is obtained by
manipulating the foot, and then
a lateral fluoroscopic image is
made to confirm that there is no
angulation or translation of the
fibula. This is the last time that
an unobstructed lateral radiograph
can be made so it is imper-
ative that any sagittal plane
displacement of the fibula is corrected
now. Once this is completed,
the anteroposterior
radiograph is made again to confirm
the coronal plane reduction.
Residual lateral translation or
angulation is often seen; this is
normal and is corrected later
with the undercontoured plate.
Next, a precontoured
direct lateral fibular plate, or a
straight one-third tubular smallfragment
plate that the surgeon
contours to the shape of the distal
aspect of the fibula, is placed
into the wound. It is vital that the
plate be slightly undercontoured
in relation to the lateral surface
of the fibula as this ultimately
corrects the lateral translation of
the fibula. The plate is placed
onto the fibula, with the surgeon
ensuring that it is centered between
the anterior and posterior
borders of the bone. This is done
initially by feel as one cannot
strip the soft tissue from the fibula
to visualize the bone directly,
but a Kirschner wire can be used
as a probe to assist in identifying
the anterior and posterior borders
of the fibula. Fluoroscopic
lateral imaging is required to
confirm that the plate is centered
on the bone before fixation
is placed (Fig. 6-A). This is paramount
for the reduction as the
direction of the force provided
by the plate must be directly medially
to reduce the laterally
translated fibula. Additionally,
the fibula must be evaluated for
angulation. Any anterior or posterior
angulation must be corrected
prior to fixation by